Since I come across this issue constantly...
#GameDev if you want your game on #SteamDeck, and you don't have a #Linux version - don't in any way tag it for Linux / SteamOS. All that does is result in a broken empty download.
Do nothing. Valve check themselves using Proton via Deck Verified.
@gamingonlinux I saw this on GoG a while ago as well. Game marked with Win, Mac and Linux but after pruchasing download option was only Windows. I just returned the game and found out later that linux build was being submitted with delay.
I always assumed that tagging is automatic based on file uploads by devs and not manually by ticking boxes ๐